HLA-B27 testing is not useful as a single diagnostic test in a patient with low back pain without further spondyloarthropathy (SpA) signs or symptoms (e.g., inflammatory back pain ≥3 months duration with age of onset <45 years, peripheral synovitis, enthesitis, dactylitis, psoriasis or uveitis) because the diagnosis of spondyloarthropathy in these patients is of low probability. If HLA-B27 is used, at least two SpA signs or symptoms, or the presence of positive imaging findings, need to be present to classify a patient as having axial SpA. There is no clinical utility to ordering an HLA-B27 in the absence of positive imaging or the minimally required SpA signs or symptoms.
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Rudwaleit M, et al. How to diagnose axial spondyloarthritis early. Ann Rheum Dis. 2004 May;63(5):535-43. PMID: 15082484.
Rudwaleit M, et al. The development of assessment of SpondyloArthritis international society classification criteria for axial spondyloarthritis (part II): Validation and final selection. Ann Rheum Dis. 2009 Jun;68(6):777-83. PMID: 19297344.
Sidiropoulos PI, et al. Evidence-based recommendations for the management of ankylosing spondylitis: Systematic literature search of the 3E initiative in rheumatology involving a broad panel of experts and practising rheumatologists. Rheumatology (Oxford). 2008 Mar;47(3):355-61. PMID: 18276738.